The Gauls of Gallia Celtica according to the testimony of Caesar called themselves Celtae in their own language (as distinct from Belgae and Aquitani), and Galli in Latin.[2] As is not unusual with ancient ethnonyms, these names came to be applied more widely than their original sense, Celtae being the origin of the term Celts itself (in its modern meaning referring to all populations speaking a language of the "Celtic" branch of Indo-European) while Galli is the origin of the adjective Gallic, now referring to all of Gaul.

The name Gaul itself may be derived from Latin Galli, or it may be derived from the Germanic word Walha.[1].

In 278 BC Gaulish settlers in the Balkans were invited by Nicomedes I of Bithynia to help him in a dynastic struggle against his brother. They numbered about 10,000 fighting men and about the same number of women and children, divided into three tribes, Trocmi, Tolistobogii and Tectosages. They were eventually defeated by the Seleucid king Antiochus I (275 BC), in a battle where the Seleucid war elephants shocked the Galatians. While the momentum of the invasion was broken, the Galatians were by no means exterminated and continued to demand tribute from the Hellenistic states of Anatolia to avoid war. 4,000 Galatians were hired as mercenaries by the Ptolemaic Egyptian king Ptolemy II Philadelphus in the 270 BC. According to Pausanias, soon after arrival the Celts plotted “to seize Egypt,” and so Ptolemy marooned them on a deserted island in the Nile River.[3]

Galatians also participated at the victorious in 217 BC Battle of Raphia under Ptolemy IV Philopator, and continued to serve as mercenaries for the Ptolemaic Dynasty until its demise in 30 BC. They sided with the renegade Seleucid prince Antiochus Hierax, who reigned in Asia Minor. Hierax tried to defeat king Attalus I of Pergamum (241–197 BC), but instead, the Hellenized cities united under Attalus's banner, and his armies inflicted a severe defeat upon the Galatians at the Battle of the Caecus River in 241 BC. After the defeat, the Galatians continued to be a serious threat to the states of Asia Minor. In fact, they continued to be a threat even after their defeat by Gnaeus Manlius Vulso in the Galatian War (189 BC). Galatia declined and fell at times under Pontic ascendancy. They were finally freed by the Mithridatic Wars, during which they supported Rome. In the settlement of 64 BC, Galatia became a client-state of the Roman empire, the old constitution disappeared, and three chiefs (wrongly styled "tetrarchs") were appointed, one for each tribe. But this arrangement soon gave way before the ambition of one of these tetrarchs, Deiotarus, the contemporary of Cicero and Julius Caesar, who made himself master of the other two tetrarchies and was finally recognized by the Romans as 'king' of Galatia. The Galatian language continued to be spoken in central Anatolia until the 6th century.[4]

During the Second Punic War the famous Carthaginian general Hannibal Barca utilized Gallic mercenaries in his famous invasion of Italy. They played a part in some of his most spectacular victories including the battle of Cannae. The Gauls were prosperous enough by the 2nd century that the powerful Greek colony of Massilia had to appeal to the Roman Republic for defense against them. The Romans intervened in southern Gaul in 125 BC, and conquered the area eventually known as Gallia Narbonensis by 121.

In 58 BC Julius Caesar launched the Gallic Wars and conquered the whole of Gaul by 51 BC. At this time Caesar noted that the Gauls (Celtae) were one of the three primary peoples in the area at the time, along with the Aquitanians and the Belgae. Caesar's motivation for the invasion seems to have been his need for gold to pay off his debts and for a successful military expedition to boost his political career. The people of Gaul could provide him with both. So much gold was looted from Gaul that after the war the price of gold fell by as much as 20%. While militarily just as strong as the Romans, the internal division between the Gallic tribes guaranteed an easy victory for Caesar, and Vercingetorix's attempt to unite the Gauls against Roman invasion came too late.[5][6] After the annexation of Gaul a mixed Gallo-Roman culture began to emerge.

The fourth-century Roman historian Ammianus Marcellinus wrote that the Gauls were tall and light-blue eyed:

Nearly all the Gauls are of a lofty stature, fair and ruddy complexion: terrible from the sternness of their eyes, very quarrelsome, and of great pride and insolence. A whole troop of foreigners would not be able to withstand a single Gaul if he called his wife to his assistance who is usually very strong and with blue eyes...[8]

All over Gaul, archeology has uncovered numerous pre-Roman gold mines (at least 200 in the Pyrenees) suggesting that they were very rich also evidenced by large finds of gold coins and artefacts. Also there existed highly developed population centers called oppida by Caesar such as Bibracte, Gergovia, Avaricum, Alesia, Bibrax, Manching and others. Modern archeology strongly suggests that the countries of Gaul were quite civilized and very wealthy. Most had contact with Roman merchants and some, particularly those that were governed by Republics such as the Aedui, Helvetii and others had enjoyed stable political alliances with Rome. They imported Mediterranean wine on an industrial scale evidenced by large finds of wine vessels in digs all over Gaul the largest and most famous of such vessels being the one discovered in Vix Grave which stands 1.63 m (5'4") in height.

Gaulish society was dominated by the druid priestly class. The druids were not the only political force, however, and the early political system was complex. The fundamental unit of Gallic politics was the tribe, which itself consisted of one or more of what Caesar called "pagi".[citation needed] Each tribe had a council of elders, and initially a king. Later, the executive was an annually-elected magistrate.[citation needed] Among the Aedui tribe the executive held the title of "Vergobret", a position much like a king, but its powers were held in check by rules laid down by the council.[citation needed]

The tribal groups, or pagi as the Romans called them (singular: pagus; the French word pays, "region", comes from this term) were organised into larger super-tribal groups that the Romans called civitates. These administrative groupings would be taken over by the Romans in their system of local control, and these civitates would also be the basis of France's eventual division into ecclesiastical bishoprics and dioceses, which would remain in place — with slight changes — until the French Revolution.

Although the tribes were moderately stable political entities, Gaul as a whole tended to be politically divided, there being virtually no unity among the various tribes. Only during particularly trying times, such as the invasion of Caesar, could the Gauls unite under a single leader like Vercingetorix. Even then, however, the faction lines were clear.

The Romans divided Gaul broadly into Provincia (the conquered area around the Mediterranean), and the northern Gallia Comata ("free Gaul" or "wooded Gaul"). Caesar divided the people of Gaulia Comata into three broad groups: the Aquitani; Galli (who in their own language were called Celtae); and Belgae. In the modern sense, Gaulish tribes are defined linguistically, as speakers of dialects of the Gaulish language. While the Aquitani were probably Vascons, the Belgae would thus probably be counted among the Gaulish tribes, perhaps with Germanic elements.

All Gaul is divided into three parts, one of which the Belgae inhabit, the Aquitani another, those who in their own language are called Celts, in ours Gauls, the third.

All these differ from each other in language, customs and laws.

The Garonne River separates the Gauls from the Aquitani; the River Marne and the River Seine separate them from the Belgae.

Of all these, the Belgae are the bravest, because they are furthest from the civilisation and refinement of (our) Province, and merchants least frequently resort to them, and import those things which tend to effeminate the mind; and they are the nearest to the Germani, who dwell beyond the Rhine, with whom they are continually waging war; for which reason the Helvetii also surpass the rest of the Gauls in valour, as they contend with the Germani in almost daily battles, when they either repel them from their own territories, or themselves wage war on their frontiers. One part of these, which it has been said that the Gauls occupy, takes its beginning at the River Rhône; it is bounded by the River Garonne, the Atlantic Ocean, and the territories of the Belgae; it borders, too, on the side of the Sequani and the Helvetii, upon the River Rhine, and stretches toward the north.

The Belgae rises from the extreme frontier of Gaul, extend to the lower part of the River Rhine; and look toward the north and the rising sun.

The Gauls practiced a form of animism, ascribing human characteristics to lakes, streams, mountains, and other natural features and granting them a quasi-divine status. Also, worship of animals was not uncommon; the animal most sacred to the Gauls was the boar, which can be found on many Gallic military standards, much like the Roman eagle.

Their system of gods and goddesses was loose, there being certain deities which virtually every Gallic person[citation needed] worshiped, as well as tribal and household gods. Many of the major gods were related to Greek gods; the primary god worshiped at the time of the arrival of Caesar was Teutates, the Gallic equivalent of Mercury. The "father god" in Gallic worship was "Dis Pater". However, there was no real theology[citation needed], just a set of related and evolving traditions of worship.

Perhaps the most intriguing facet of Gallic religion is the practice of the Druids. There is no certainty concerning their origin, but it is clear that they vehemently guarded the secrets of their order and held sway over the people of Gaul. Indeed, they claimed the right to determine questions of war and peace, and thereby held an "international" status. In addition, the Druids monitored the religion of ordinary Gauls and were in charge of educating the aristocracy. They also practiced a form of excommunication from the assembly of worshippers, which in ancient Gaul meant a separation from secular society as well. Thus the Druids were an important part of Gallic society.

After completing the conquest of Gaul, Rome converted most of these tribes into civitates, making for the administrative map of the Roman provinces of Gaul. This was then perpetuated by the early church, whose geographical subdivisions were based on those of late Roman Gaul, and lasted into the areas of French dioceses prior to the French Revolution.

The Gauls played a certain role in the national historiography and national identity of modern France. Attention given to the Gauls as the founding population of the French nation was traditionally second to that enjoyed by the Franks, out of whose kingdom the historical kingdom of France arose under the Capetian dynasty; for example, Charles de Gaulle is on record as stating, "For me, the history of France begins with Clovis, elected as king of France by the tribe of the Franks, who gave their name to France. Before Clovis, we have Gallo-Roman and Gaulish prehistory. The decisive element, for me, is that Clovis was the first king to have been baptized a Christian. My country is a Christian country and I reckon the history of France beginning with the accession of a Christian king who bore the name of the Franks." [11]

However, the dismissal of "Gaulish prehistory" as irrelevant for French national identity has been far from universal. Pre-Roman Gaul has been evoked as a template for French independence especially during the Third French Republic. An iconic phrase summarizing this view is that of "our ancestors the Gauls" (nos ancêtres les Gaulois), associated with the history textbook for schools by Ernest Lavisse (1842-1922), who taught that "the Romans established themselves in small numbers; the Franks were not numerous either, Clovis having but a few thousand men with him. The basis of our population has thus remained Gaulish. The Gauls are our ancestors."[12]

Astérix, the popular series of French comic books following the exploits of a village of "indomitable Gauls", satirizes this view by combining scenes set in classical antiquity with modern ethnic clichés of the French and other nations.

Similarly, in Swiss national historiography of the 19th century, the Gaulish Helvetii were chosen as representing the ancestral Swiss population (compare Helvetia as national allegory), as the Helvetii had settled in both the French and the German-speaking parts of Switzerland, and their Gaulish language set them apart from Latin and German speaking populations in equal measure.

^Koch, John T. (2006). "Galatian language". In John T. Koch. Celtic culture: a historical encyclopedia. Volume III: G—L. Santa Barbara, California: ABC-CLIO. p. 788. ISBN1-85109-440-7. Late classical sources—if they are to be trusted—suggest that it survived at least into the 6th century AD.

^"Julius Caesar: The first triumvirate and the conquest of Gaul". Encyclopædia Britannica Online. Encyclopædia Britannica. Retrieved February 15, 2015. Indeed, the Gallic cavalry was probably superior to the Roman, horseman for horseman. Rome’s military superiority lay in its mastery of strategy, tactics, discipline, and military engineering. In Gaul, Rome also had the advantage of being able to deal separately with dozens of relatively small, independent, and uncooperative states. Caesar conquered these piecemeal, and the concerted attempt made by a number of them in 52 bce to shake off the Roman yoke came too late.